LAUSR

To determine the effect of various trace mineral-containing products on trace mineral status of cattle 56 Angus-cross steers (303 ± 15 kg; n = 8 per treatment) were blocked by BW and administered a trace mineral treatment on d-0: injectable saline (CON), injectable Multimin®90 (ITM), MineralMax drench (MMD), MineralMax paste (MMP), Starting Fluid Drench (SFD), Se365 bolus (Se365), or Reloader250 bolus (Rel250). Steers received a common diet (silage-based d 0–49; corn-based d 50–122) via bunks capable of measuring individual feed disappearance. Plasma (0, 8, 24, and 48-h) and liver (-7, 2, 15, 29, 49, 65, 91, and 120-d) samples were obtained for analysis of Cu, Mn, Se, and Zn. Data were analyzed as repeated measures with effects of treatment, time, and treatment×time, with initial mineral concentration as covariate. Plasma Zn, Mn, and Se concentrations were affected by treatment×time (P = 0.001) where ITM was greater through 8-h for Zn and through 24-h for Mn and Se over all other treatments. Liver Se concentration was greater in ITM vs. other treatments through d-15 and Rel250 was greater than ITM and MMP on d-91 and greater than CON, MMD, MMP, and SFD on d-120 (treatment×time; P ≤ 0.001). Plasma Cu, and liver Cu, Mn, and Zn concentrations were unchanged by treatment (P ≥ 0.05). Liver Mn concentrations were least on d-2 and generally increased over time (P ≤ 0.001), while liver Zn concentrations were greatest on d-2 and least from d-29 onward (time; P ≤ 0.001). Liver Cu concentrations were greatest on d-15 and d-29 vs. other days (time; P ≤ 0.001). Overall, use of injectable trace mineral rapidly increased plasma Mn, Se and Zn, and liver Se concentrations. Oral treatments tested here exerted no effect on plasma or liver concentrations, while the multi-element bolus, Rel250, increased liver Se after 91-d.